This application to the NIH Shared Instrumentation Grants Programs funds to purchase a Confocal Imaging Microscope. Nine research faculty from the Departments of Ophthalmology and Otolaryngology at Harvard Medical School will form the major user group for this resource. This group, located at the Massachusetts Eye and Ear Infirmary (MEEI), has joined in an effort to develop a new imaging microscopy center for structure and function studies in vision and hearing. We seek a state-of-the-art instrument that provides exceptionally high resolution to image small neuronal and support cells in retinal or cochlear tissues. Our work ranges across species, but includes examining immunofluorescently marked cells, protein or nucleic acid complexes, and tissues from transgenic animals (Drosophila, Zebrafish, mice) carrying reporter constructs. The instrument must be maximized for low level illumination and high detection to minimize sample bleaching and damage. In addition, we seek the ability to optically section molecular ensembles or marked cells to generate serially constructed 3-D images in order to co-localized molecular structures and to trace long neurons through sections. For a core facility we request a spectral confocal microscope that will provide flexibility of using several fluorophore markers and enhance the ability to accurately co-localize two or more marked structures. The instrument sought is configured to enable upgrading with additional excitation sources or multi-photon use for future applications. A plan is offered for administration, training, and maintenance of this facility, which will be shared by the vision and hearing groups over the coming years. The confocal microscope imaging facility brings new technical possibilities for discovery in vision and hearing research now supported by our many NIH research grants.